TAMPA — In Hillsborough County’s priciest transaction in a year, a South Florida firm paid $145.75 million for the Grand Hyatt Tampa Bay and the Bayport Plaza office park in the Rocky Point area. The sale was announced earlier this week before the deed had been recorded. IP Capital Partners bought the 444-room waterfront hotel and 266,000-square-foot office park from Bayport Drive Hotel Investors, which had owned it since 2010. The purchase price at that time was $55.57 million. “Large waterfront sites in Tampa are increasingly rare, and there was a significant amount of interest to finance two premier assets,” said Chris Drew of JLL Hotels and Hospitality, which advised on the sale and arranged financing.